首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 156 毫秒
1.
为明确氮素形态耦合及土壤氮转化过程调控措施对作物氮肥利用率的影响,在田间试验条件下研究了不同铵态氮肥用量(纯氮225.0、168.8和112.5 kg/hm2)±硝化抑制剂、不同硝态氮肥用量(纯氮225.0、168.8和112.5 kg/hm2)对马铃薯生长的影响。研究结果显示,与施用硝态氮肥相比,铵态氮肥的施用显著提高了马铃薯的产量和氮素吸收量;随铵态氮肥用量的提高,马铃薯产量具有增加的趋势,而不同硝态氮肥用量处理对马铃薯薯块产量无显著影响;铵态氮肥配施双氰胺(DCD)可以有效提高土壤铵态氮含量,增加马铃薯薯块产量(特别是大中薯产量)。马铃薯产量与土壤铵态氮含量呈显著正相关关系,与硝态氮含量没有明显关系。研究结果说明氮素形态耦合能够促进作物生长、提高作物氮肥利用率,对氮肥减量增效具有重要的指导意义。  相似文献   

2.
长期不同施肥处理对土壤活性氮库的影响   总被引：5，自引：0，他引：5  
通过长期肥料定位试验,对不同施肥处理下草甸黑土活性氮库中几种重要组分含量变化及其相互之间的比例关系进行研究.结果表明,氮肥施用能够增加土壤中无机氮含量,以土壤剖面中硝态氮含量变化为例,除NPK配施处理外,其它施氮处理在180-200 cm土层硝态氮含量均显著增加,N,.P,K配施减少了土壤剖面中硝态氮累积.土壤表层微生物态氮和固定态铵含量的变化不仅取决于氮素的投入量,还与其它因素有关,长期单纯施用氮肥土壤微生物氮含量并没有增高.而N,P配施的处理,土壤微生物氮含量较高.施用氮肥抑制了土壤中可矿化氮的含量,促进氮的矿化释放,增加了活性氮库中其它组分的含量;不同施肥处理表层土壤氮素矿化速率从高到低的顺序是:CKPKPKNPNPKNKN,不同施肥处理对硝化速率的影响大小按PCKKPKNPNPKNNK顺序排列.  相似文献   

3.
梁斌  赵伟  杨学云  周建斌 《土壤学报》2012,49(4):748-757
以长期不同施肥处理土壤为对象,研究了不同施肥土壤中施用氮肥后土壤氮素含量、微生物固持及释放和作物吸收及利用特性。结果表明,施用氮肥显著增加长期不施肥土壤(NF)矿质氮含量,对长期施用化肥土壤(NPK)和有机无机配施土壤(MNPK)矿质态氮含量无显著影响;施用氮肥对NF中土壤微生物生物量氮(SMBN)含量无显著影响,使拔节期NPK和MNPK中SMBN含量分别增加了4.3倍和0.8倍。从小麦拔节期到开花期,NPK和MNPK中土壤微生物生物量氮含量分别显著降低51%和56%。小麦收获时NPK和MNPK土壤氮肥的利用率分别为36%和45%;而NF土壤所施入的氮素几乎未被小麦吸收利用,但在玉米季有34%被吸收。小麦收获时,NF土壤施入的氮肥有50%以上淋溶至土壤30 cm以下土层,施氮也显著提高了NPK土壤30～50 cm土层硝态氮含量,但施用氮肥对MNPK土壤0～100 cm剖面硝态氮含量无显著影响。说明长期有机无机配施增强了土壤氮素的缓冲能力,协调了土壤氮素固持与作物吸氮间的关系,为提高氮素利用率,减少氮素对环境影响的有效手段。  相似文献   

4.
过维钧  刘茂林 《土壤》1978,10(6):217-219,212
氮素是作物营养的主要成份,作物吸收氮素的量总是大大超过土壤直接供应的量,施用氮肥是农作物增产的重要手段,随着化学工业的发展,化肥使用量逐步增加,但由于施入土壤的氮素化肥受土壤微生物的作用,转化为土壤难于保蓄的硝态氮或气态氮化合物,造成氮素的损失,这个过程亦称为土壤的脱氮作用。  相似文献   

5.
滴灌施肥条件下不同种类氮肥在土壤中迁移转化特性的研究   总被引：30，自引：2，他引：30  
采用室内土柱模拟方法研究了滴灌条件下不同种类氮肥(硝态氮、铵态氮和尿素态氮)在土壤中的迁移、淋溶和转化特征。结果表明,3种氮肥在2种质地土壤中的淋失量均是硝态氮肥>尿素>铵态氮肥,淋失的氮素主要为肥料氮。砂壤土上氮素的淋失量明显高于粘壤土。滴灌施用铵态氮肥,显著增加了土壤中NH4+-N含量,随着硝化作用的进行,NH4+-N的量在培养的第5d左右达高峰,尔后含量逐渐降低。与滴灌施用硝态氮肥相比,施用铵态氮肥和尿素后在培养期间土壤矿质态氮(NO3--N+NH4+-N)的含量有降低的趋势，降低的原因可能与N+NH4+-N在土壤中的固定、挥发等有关。  相似文献   

6.
长期施肥条件下华北平原农田硝态氮淋失风险的研究   总被引：41，自引：9，他引：41  
利用河北辛集潮土(21年)和北京昌平褐潮土(9年)两个长期定位施肥试验研究了华北平原冬小麦夏玉米轮作体系下农田氮素平衡和硝态氮淋失风险。结果表明,单施氮肥的增产效果有限,昌平试验点甚至出现减产现象;而适量有机肥与氮磷或氮磷钾配施可显著提高作物产量,降低氮素盈余。单施氮肥时,辛集和昌平土壤硝态氮峰值分别达20.7和30.0.mg/kg,出现在160200.cm和90120.cm土层;硝态氮累积量高且大部分集中在根区外土壤,硝态氮淋失风险大。氮磷或氮磷钾肥配施时,硝态氮峰值出现深度上移3040cm,根区和根区外土壤硝态氮累积量均大幅降低,淋失风险明显减弱;在氮磷或氮磷钾肥基础上适量施用有机肥时,硝态氮峰值出现深度进一步上移至根区土壤,深层土壤硝态氮累积量显著下降,淋失风险低。过量施用有机肥或过量施用氮肥时,深层土壤硝态氮累积量大幅增加,甚至超过单施氮肥处理,淋失风险大大增强。研究结果表明,氮磷钾肥与有机肥配合施用是提高作物产量、控制农田硝态氮淋失的重要途径。  相似文献   

7.
旱地土壤硝态氮与氮素平衡、氮肥利用的关系   总被引：9，自引：5，他引：4  
利用长期肥料试验资料研究了土壤氮素平衡、氮肥利用率和土壤硝态氮之间的相互关系。结果表明,小麦不同施肥处理的氮肥利用率（NUE）为30.9%~65.8%,平均53.6%;土壤硝态氮累积率2.3%~44.1%,平均13.2%;氮素表观损失率25.0%~42.7%,平均33.2%。一般情况下,氮素盈余值与氮肥用量呈正相关,与磷肥用量呈负相关;土壤中硝态氮的数量与氮素盈余值呈正比,与氮肥利用率呈反比。黄土旱塬地区,小麦在经济合理施氮条件下,氮素盈余值为13.79 kg/hm2,硝态氮累积量为23.00 kg/hm2,说明过量施用一定数量的氮肥对保持作物生产力和土壤氮素营养是必要的。  相似文献   

8.
研究了不同氮肥运筹对土壤硝态氮时空分布及小麦氮肥利用效率的影响。结果表明,小麦氮素利用效率随施氮量的增加而显著降低,增加追肥比例提高了产量和氮肥利用效率,品种间趋势一致。0～60 cm土层土壤硝态氮含量冬前最高,随着生育进程而逐渐降低。随施氮量增加土壤硝态氮含量升高,特别是下层土壤硝态氮含量在施氮处理下更为明显。从播种至成熟,不施氮处理土壤氮素出现了表观亏缺,施氮处理均表现氮素盈余,且随施氮量的增加而增加。因此,在小麦生产中应避免在播种时一次性大量施用氮肥,而分期施肥有利于小麦吸收利用,并且可以减少深层土壤硝态氮的累积。  相似文献   

9.
长期施肥对农田土壤氮素关键转化过程的影响   总被引：32，自引：0，他引：32  
王敬  程谊  蔡祖聪  张金波 《土壤学报》2016,53(2):292-304
当前,如何合理施肥、提高作物产量、维持土壤肥力、并兼顾生态环境效应是农业研究的主要挑战之一。本文综述了长期施肥对农田土壤氮素关键转化过程的影响,主要从土壤氮转化过程的初级转化速率角度综述肥料(有机肥和化学氮肥)对土壤氮素关键转化过程的影响。土壤氮素矿化-同化循环是自然界氮循环过程中两个至关重要的环节,是决定土壤供氮能力的重要因素。总体而言,长期施用氮肥,尤其是有机肥能显著提高初级矿化-同化周转速率;长期施肥可以刺激自养硝化作用,且有机肥的刺激作用更明显;施用化学氮肥和有机肥均能提高反硝化速率,且有机肥的刺激作用高于化学氮肥。有机肥一直被提倡和实践用来改善土壤肥力和提高土壤固碳能力,无论是单施有机肥还是有机-无机配施,均能有效地减轻硝酸盐污染,改善土壤肥力并提高作物产量。但是有机肥的施用并不是多多益善,有机肥过多施用也会增加氮损失的风险。因此,本文综述了长期施肥对农田土壤氮素关键转化过程初级转化速率的影响,讨论了各个氮转化过程之间的联系,以期增强人们对长期施肥措施影响农田土壤氮素循环的理解,并为合理施用氮肥、提高氮肥利用率、减少与氮相关的环境污染提供理论依据。  相似文献   

10.
生物炭对植烟土壤氮素形态迁移及微生物量氮的影响   总被引：2，自引：0，他引：2  
为了在植烟土壤中施加生物炭,以及在不同氮素水平下验证生物炭对土壤氮素的淋洗及迁移的影响.采用大田试验,设计5个处理,在磷肥和钾肥施用量相同的基础上,除对照(CK)处理不施生物炭与氮肥外,其余4个处理都添加1 600 kg/hm2的生物炭,施氮量分别为(N0)0、(N1)37.5、(N2)52.5和(N3) 67.5 kg/hm2,对植烟土壤氮素在0～20、20 ～ 40和40 ～ 60 cm土层施加生物炭,研究全氮、碱解氮、硝态氮和铵态氮质量分数的影响及其迁移规律,以及0～20cm土层微生物量氮的变化特征.结果表明:植烟土壤施用生物炭降低了0～ 20 cm以下土壤氮素质量分数,提高了植烟土壤对氮素的固定能力.与CK相比,增施生物炭的N0在0～20 cm以下土层,土壤全氮、碱解氮、硝态氮和铵态氮质量分数降低率最高达到11.21％、49.07％、42.29％和31.35％.而施氮量对植烟土壤全氮、碱解氮和铵态氮的影响,主要集中在0 ～ 20 em土层,且土壤氮素质量分数随施氮量的增加而增加,以N3处理各氮素指标质量分数相对最高,其全氮、碱解氮和铵态氮质量分数最高分别为2.10 g/kg、261.86 mg/kg和49.80 mg/kg.土壤硝态氮质量分数随土层加深而下降,在0 ～ 20 cm土层,以N3处理最高,达264.90 mg/kg;但不同氮水平下,硝态氮质量分数在20 ～ 40 cm土层差异较其他土层更显著.施用氮肥对植烟土壤氮素的影响主要表现在烟草移栽后前30 d.增施生物炭可以提高烟草移栽后60 d时土壤微生物量氮;而施氮量对微生物量氮熵的影响主要表现在烟草移栽30 d之后.施氮量对植烟土壤氮素的影响主要表现在0～20 cm土层,且在烟草生育前期效果显著.生物炭可以明显抑制植烟土壤本身及低量氮肥施用下氮素淋失迁移,但在高量氮肥施用下的抑制作用不明显.在豫中烟区,以生物炭配施氮肥67.5 kg/hm2施肥措施,最利于植烟土壤氮素提高.  相似文献   

11.
Soils are the major source of the greenhouse gas nitrous oxide (N2O) to our atmosphere. A thorough understanding of terrestrial N2O production is therefore essential. N2O can be produced by nitrifiers, denitrifiers, and by nitrifiers paradoxically denitrifying. The latter pathway, though well-known in pure culture, has only recently been demonstrated in soils. Moreover, nitrifier denitrification appeared to be much less important than classical nitrate-driven denitrification. Here we studied a poor sandy soil, and show that when moisture conditions are sub-optimal for denitrification, nitrifier denitrification can be a major contributor to N2O emission from this soil. We conclude that the relative importance of classical and nitrifier denitrification in N2O emitted from soil is a function of the soil moisture content, and likely of other environmental conditions as well. Accordingly, we suggest that nitrifier denitrification should be routinely considered as a major source of N2O from soil.  相似文献   

12.
To understand the contribution of key microbial processes to nitrous oxide (N2O) emission in intensively cultivated black soil, laboratory incubation were conducted at 70% water-holding capacity (WHC) and 25 °C, using different gases (air, oxygen, or argon) within the headspace of the incubation chambers to evaluate gas inhibition effects. Arable black soil was sampled from an experimental field that has received urea since October 1979. Nitrification contributed to 57% of total N2O emission, of which as much as 67% resulted from heterotrophic nitrification. These data strongly suggest that high soil organic carbon concentrations and low pH values are more favorable to N2O production through heterotrophic, rather than autotrophic, nitrification. Nitrous oxide produced by denitrification accounted for 28% of the total N2O emission, and the nitrifier denitrification accounted for 15% of the N2O emitted from the tested soil. These findings indicate that heterotrophic nitrification was the primary N2O production process in the tested soil.  相似文献   

13.
《Soil biology & biochemistry》2001,33(12-13):1723-1732
Nitrifier denitrification is the pathway of nitrification in which ammonia (NH3) is oxidized to nitrite (NO2−) followed by the reduction of NO2− to nitric oxide (NO), nitrous oxide (N2O) and molecular nitrogen (N2). The transformations are carried out by autotrophic nitrifiers. Thus, nitrifier denitrification differs from coupled nitrification–denitrification, where denitrifiers reduce NO2− or nitrate (NO3−) that was produced by nitrifiers. Nitrifier denitrification contributes to the development of the greenhouse gas N2O and also causes losses of fertilizer nitrogen in agricultural soils. In this review article, present knowledge about nitrifier denitrification is summarized in order to give an exact definition, to spread awareness of its pathway and controlling factors and to identify areas of research needed to improve global N2O budgets. Due to experimental difficulties and a lack of awareness of nitrifier denitrification, not much is known about this mechanism of N2O production. The few measurements carried out so far attribute up to 30% of the total N2O production to nitrifier denitrification. Low oxygen conditions coupled with low organic carbon contents of soils favour this pathway as might low pH. As nitrifier denitrification can lead to substantial N2O emissions, there is a need to quantify this pathway in different soils under different conditions. New insights attained through quantification experiments should be used in the improvement of computer models to define sets of conditions that show where and when nitrifier denitrification is a significant source of N2O. This may subsequently render the development of guidelines for low-emission farming practices necessary.  相似文献   

14.
森林土壤氧化亚氮排放对大气氮沉降增加的响应研究进展   总被引：1，自引：1，他引：1  
森林土壤N2O来源于土壤氮素的氧化还原反应,硝化、反硝化、硝化细菌反硝化以及化学反硝化是其产生的四个关键过程。当前,氮素富集条件下森林土壤N2O排放存在硝化和反硝化主导作用之争,对大气氮沉降增加的响应模式以及微生物驱动机制尚不清楚。综述了森林土壤N2O来源的稳定性同位素拆分,森林土壤总氮转化和N2O排放对增氮的响应规律,增氮对N2O产生菌群落活性和组成的影响,并指出研究的薄弱环节与未来的研究重点。总体而言,森林土壤N2O排放对大气氮沉降增加的响应呈现非线性,包括初期无明显响应、中期缓慢增加和后期急剧增加三个阶段,取决于森林生态系统"氮饱和"程度。施氮会引起森林土壤有效氮由贫氮向富氮的转变,相应地改变了土壤硝化细菌和反硝化细菌群落丰度与组成,进而影响土壤N2O排放。由于森林土壤N2O排放监测、土壤总氮转化和N2O产生菌群落动态研究多为独立进行的,难以阐明微生物功能群与N2O排放之间的耦合关系。未来研究应该有机结合15N-18O标记和分子生物学技术,准确量化森林土壤N2O的来源,揭示森林土壤N2O排放对增氮的非线性响应机理。  相似文献   

15.
Summary A sandy soil amended with different forms and amounts of fertilizer nitrogen (urea, ammonium sulphate and potassium nitrate) was investigated in model experiments for N2O emission, which may be evolved during both oxidation of ammonia to nitrate and anaerobic respiration of nitrate. Since C2H2 inhibits both nitrification and the reduction of N2O to N2 during denitrification, the amount of N2O evolved in the presence and absence of C2H2 represents the nitrogen released through nitrification and denitrification.Results show that amounts of N2O-N lost from soils incubated anaerobically with 0.1% C2H2 and treated with potassium nitrate (23.1 µg N-NO 3 – /g dry soil) exceeded those from soils incubated in the presence of 20% oxygen and treated with even larger amounts of nitrogen as urea and ammonium sulphate. This indicates that nitrogen losses by denitrification may potentially be higher than those occurring through nitrification.  相似文献   

16.
Croplands are an important source of atmospheric methane (CH4) and nitrous oxide (N2O), both potent greenhouse gases. Reduction of cropland CH4 and N2O emissions is expected to mitigate climate change. However, large uncertainty remains in the assessment and prediction of these emissions, which prevents us from establishing appropriate mitigation options and strategies. The uncertainty is attributed mainly to the high spatiotemporal variability in emissions (e.g., emission spikes of N2O). Understanding and quantifying how hotspots of CH4 and N2O production in soil and then hot moments of their emissions occur would help reduce the uncertainty. This review focuses on soil–plant systems, particularly the rhizosphere, as possible hotspots of production and consumption of CH4 and N2O. It is well known that the rhizosphere controls CH4 emission strongly, though each process of production and consumption remains to be quantified. On the other hand, surprisingly little attention has been paid to N2O, besides the fact that plant roots strongly control nitrification and denitrification. We review the current knowledge of cropland CH4 and N2O emissions, and conclude that soil–plant interactions strongly affect cropland emissions of both gases, in which functions of plant roots affecting biogeochemical factors (e.g., availability of oxygen, labile organic carbon and inorganic nitrogen) in the rhizosphere and phenological changes are particularly important. In relation to the status of current knowledge, we discuss future research needed.  相似文献   

17.
We studied the effect of repeated application (once every 2 d) of a fertilizer solution with different ratios of NH4 + - and NO3 ?-N on N2O emission from soil. After the excess fertilizer solution was drained from soil, the water content of soil was adjusted to 50% of the maximum water-holding capacity by suction at 6 × 103 Pa. Repeated application of NH4 +- rich fertilizer solution stimulated nitrification in soil more than NO3 ?-rich fertilizer. Although the evolution of N2O through nitrifier denitrification tended to increase with the repeated addition of a fertilizer solution rich in NH4 + rather than in NO3 ?, the contribution of nitrifier denitrification remained at levels of 20 to 36% of the total emission regardless of the inorganic N composition. The total emission of N2O also tended to increase with the application of NH4 +- rather than NO3 ?-rich fertilizer. It was suggested that the coupled process of nitrification and denitrification at micro-aerobic sites became important when fertilizer rich in NH4 + was applied to soil under relatively aerobic conditions.  相似文献   

18.
硝化反应是土壤、特别是干旱半干旱地区农业土壤N2O产生的重要途径之一。但是,目前环境条件对硝化反应中N2O排放的影响研究较少,而在国内外通用的几个模型中均用固定比例估算硝化反应过程中N2O的排放。本文通过砂壤土培养试验,研究了土壤温度、水分和NH4+-N浓度对硝化反应速度及硝化反应中N2O排放的影响,并用数学模型定量表示了各因素对硝化反应的作用,用最小二乘法最优拟合求得该土壤的最大硝化反应速度及N2O最大排放比例。结果表明,随着温度升高,硝化反应速度呈指数增长;水分含量由20%充水孔隙度(WFPS)增加到40%WFPS时,反应速度增加,水分含量增加到60%WFPS时反应速度略有降低;NH4+-N浓度增加对硝化反应速度起抑制作用。用米氏方程描述该土壤的硝化反应过程,其最大硝化反应速度为6.67mg·kg?1·d?1。硝化反应中N2O排放比例随温度升高而降低;随NH4+-N浓度增加而略有增加;20%和40%WFPS水分含量时,硝化反应中N2O排放比例为0.43%～1.50%,最小二乘法求得的最大比例为3.03%,60%WFPS时可能由于反硝化作用,N2O排放比例急剧增加,还需进一步研究水分对硝化反应中N2O排放的影响。  相似文献   

19.
施肥对夏玉米季紫色土N2O排放及反硝化作用的影响   总被引：9，自引：0，他引：9  
采用原状土柱-乙炔抑制培养法研究了施肥对紫色土玉米生长季土壤N2O排放通量和反硝化作用的影响.结果表明:玉米季施肥显著增加土壤N2O排放和反硝化损失,同时,各施肥处理间N2O排放与反硝化损失量差异显著.猪厩肥、猪厩肥配施氮磷钾肥、氮肥、氮磷钾肥和秸秆配施氮磷钾肥等处理的土壤N,O排放量分别为3.01、2.86、2.51、2.19和1.88 kg hm-2,分别占当季氮肥施用量的1.63％、1.53％、1.30％、1.09％和0.88％,反硝化损失量分别为6.74、6.11、5.23、4.69和4.12 kg hm-2,分别占当季氮肥施用量的3.97％、3.55％、2.97％、2.61％和2.23％,不施肥土壤的N2O排放量和反硝化损失量仅为0.56和0.78 kg hm-2.施肥是紫色土玉米生长前期(2周内)土壤N2O排放和反硝化速率出现高峰的主要驱动因子,土壤铵态氮和硝态氮含量是影响土壤N2O排放、土壤硝化和反硝化作用的限制因子,土壤含水量是重要影响因子,降雨是主要促发因素.土壤N2O排放量与反硝化损失量的比值介于0.45 ～0.72之间,土壤反硝化损失量极显著高于土壤N2O排放量,说明土壤反硝化作用是紫色土玉米生长季氮肥损失的重要途径.  相似文献   

20.
Nitrifier denitrification is the reduction of NO2− to N2 by nitrifiers. It leads to the production of the greenhouse gas nitrous oxide (N2O) as an intermediate and possible end product. It is not known how important nitrifier denitrification is for the production of N2O in soils. We explored N2O production by nitrifier denitrification in relation to other N2O producing processes such as nitrification and denitrification under different soil conditions. The influence of aeration of the soil, different N sources, and pH were tested in four experiments. To differentiate between sources of N2O, an incubation method with inhibitors was used [Biol. Fertil. Soils 22 (1996) 331]. Sets of four incubations included controls without addition of inhibitors, incubations with addition of small concentrations of C2H2 (0.01-0.1 kPa), large concentrations of O2 (100 kPa), or a combination of C2H2 and O2. The results indicate that the availability of NO2− stimulated the apparent N2O production by nitrifier denitrification. A decreasing O2 content increased the total N2O production, but decreased N2O production by nitrifier denitrification. No significant effect of pH could be found. The study revealed problems concerning the use of the inhibitors C2H2 and O2. Almost one-third of all incubations with inhibitors produced more N2O than the controls. Possible reasons for the problems are discussed. The inhibitors C2H2 and O2 need to be tested thoroughly for their effects on different N2O producing processes before further application.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号